Radio Terminal and Transmission Power Control Method

1. A radio terminal, comprising: a first gain control part configured to have a first gain switchable between a first level and a second level; a second gain control part configured to continuously control a second gain; and a control part configured to control operations of the first gain control part and the second gain control part, wherein a first range of a combined gain of the first gain and the second gain, the first range being obtained with a gain control by the second gain control part with the first gain control part having the first gain set at the first level, and a second range of the combined gain, the second range being obtained with the gain control by the second gain control part with the first gain control part having the first gain set at the second level, have at least an overlap, and the control part is configured to switch the first gain from one of the first level and the second level to another one of the first level and the second level in response to the combined gain being within the overlap and a change required for the combined gain exceeding a predetermined value, or in response to the combined gain being within the overlap and the radio terminal being in a period of no transmission or reception in a situation of intermittent transmission or reception.

2. The radio terminal as claimed in claim 1 , wherein a control range of transmission power from the power at the combined gain is wider with the other one of the first level and the second level than with the one of the first level and the second level.

3. A radio terminal, comprising: a first gain control part configured to have a first gain switchable between a first level and a second level; a second gain control part configured to continuously control a second gain; and a control part configured to control operations of the first gain control part and the second gain control part, wherein a first range of a combined gain of the first gain and the second gain, the first range being obtained with a gain control by the second gain control part with the first gain control part having the first gain set at the first level, and a second range of the combined gain, the second range being obtained with the gain control by the second gain control part with the first gain control part having the first gain set at the second level, have at least an overlap, and the control part is configured to set the first gain at the first level in the first gain control part in response to a desired level of the combined gain being in the overlap and a difference between the desired level of the combined gain and one of ends of the first range of the combined gain which one is nearer to the desired level being greater than a difference between the desired level of the combined gain and one of ends of the second range of the combined gain which one is nearer to the desired level.

4. A radio terminal, comprising: a first gain control part configured to have a first gain switchable between a first level and a second level; a second gain control part configured to continuously control a second gain; and a control part configured to control operations of the first gain control part and the second gain control part, wherein a first range of a combined gain of the first gain and the second gain, the first range being obtained with a gain control by the second gain control part with the first gain control part having the first gain set at the first level, and a second range of the combined gain, the second range being obtained with the gain control by the second gain control part with the first gain control part having the first gain set at the second level, have at least an overlap, and the control part is configured to switch the first gain from one of the first level and the second level to another one of the first level and the second level based on a transmission power range determined based on a handover threshold, neighbor radio base station information, and a power level obtained by measuring a reception level of a serving base station and one obtained by scanning a neighbor base station.

5. The radio terminal as claimed in claim 4 , wherein the control part is configured to switch the first gain from the one of the first level and the second level to the other one of the first level and the second level so as to widen a coverage of the transmission power range.

6. The radio terminal as claimed in claim 4 , wherein the control part is configured to set the first gain to a lower one of the first level and the second level when some of the transmitting power required to handover to each neighbor radio base station are covered at the control range of transmission power with the first gain set to the lower one of the first level and the second level.

7. A transmission power control method in a radio terminal having a first gain control part configured to have a first gain switchable between a first level and a second level and a second gain control part configured to continuously control a second gain, wherein: a first range of a combined gain of the first gain and the second gain, the first range being obtained with a gain control by the second gain control part with the first gain control part having the first gain set at the first level, and a second range of the combined gain, the second range being obtained with the gain control by the second gain control part with the first gain control part having the first gain set at the second level, have at least an overlap, and the first gain is switched from a first one of the first level and the second level to a second one of the first level and the second level in response to the combined gain being within the overlap and a change in the combined gain exceeding a predetermined value, in response to the combined gain being within the overlap and the radio terminal being in a period of no transmission or reception in intermittent transmission or reception, in response to a desired level of the combined gain being in the overlap and a difference between the desired level of the combined gain and one of ends of the first range of the combined gain which one is nearer to the desired level being greater than a difference between the desired level of the combined gain and one of ends of the second range of the combined gain which one is nearer to the desired level, or in response to obtaining a handover threshold, neighbor radio base station information, and a power level obtained by measuring a reception level of a serving base station and one obtained by scanning a neighbor base station.